Following aortic reconstruction, the viability of the sigmoid colon can most reliably be evaluated by

Viability of the colon can be evaluated intraoperatively by Doppler auscultation of the bowel mesentery and serosa, observation of bowel peristalsis, and measurement of the IMA stump pressure. A strong, pulsatile Doppler signal in the mesentery; active sigmoid peristalsis; a chronically occluded IMA; or a patent IMA with stump pressure greater than 40 mm Hg presage viability of the sigmoid colon postoperatively. However, none of these observations excludes the possibility of late sigmoid ischemia. Serial postoperative sigmoidoscopic examination is the best predictor of ischemic colitis and in experienced hands allows assessment of the depth of ischemic injury before frank perforation has occurred. Barium enema is not as accurate as sigmoidoscopy in determining depth of injury and carries grave risks of contamination by barium and feces if perforation occurs.